Complication Avoidance in Minimally Invasive Neurosurgery

Although minimally invasive neurosurgery (MIN) holds the potential for reducing the approach-related impact on normal brain, bone, and soft tissues, which must be manipulated in more conventional transcranial microneurosurgery, the techniques necessary to perform minimally invasive, yet maximally effective neurosurgery place significant demands on the surgeon because in many ways the more limited exposure creates a number of unique ways these operations can go wrong. Safe and effective MIN requires the conscious institution of specific alterations to the surgeon’s usual operative case flow, which are designed to make specific well-known mistakes impossible or at least very unlikely. Thus, it is important for the aspiring MIN surgeons to learn from the mistakes of their predecessors and to institute patterns of behavior that prevent a repetition of these mistakes. This article provides practical information regarding known pitfalls in intraventricular and transcranial neuroendoscopic surgeries and practical methods to reduce the incidence of these complications to the lowest rate possible.

Although minimally invasive neurosurgery (MIN) holds the potential for reducing the approach-related impact on normal brain, bone, and soft tissues, which must be manipulated in more conventional transcranial microneurosurgery, the techniques necessary to perform minimally invasive, yet maximally effective neurosurgery place significant demands on the surgeon because in many ways the more limited exposure creates a number of unique ways these operations can go wrong. Safe and effective MIN requires the conscious institution of specific alterations to the surgeon’s usual operative case flow, which are designed to make specific well-known mistakes impossible or at least very unlikely. Thus, it is important for the aspiring MIN surgeons to learn from the mistakes of their predecessors and to institute patterns of behavior that prevent a repetition of these mistakes. This article provides practical information regarding known pitfalls in intraventricular and transcranial neuroendoscopic surgeries and provides practical methods to reduce the incidence of these complications to the lowest rate possible.

Pitfall #1: Lack of necessary equipment or equipment failure

This pitfall category roughly encompasses a large number of potential mistakes, all of which are significantly problematic and avoidable. It is important to view endoscopic surgery in the model of the airline industry, in that the beginning of each procedure should involve a systematic and stereotyped evaluation of the equipment needed to perform the procedure in question. Most importantly, the presence of each endoscope needed to perform the planned procedure needs to be confirmed, and the function and image quality of these endoscopes need to be evaluated. Ideally, this evaluation should be performed before the induction of general anesthesia but certainly must be done before skin incision. Further, all working cannulas or sheaths and all introducing devices need to be present and confirmed to be correct for the endoscopes in use. If specifically instrumentation (eg, monopolar cautery, graspers, suction tubing) is needed, it should be confirmed that it is present and functioning and that it will fit down the working channel of the endoscope used. If image guidance is to be used, it should be confirmed to be appropriately registered and to have image probes or other device adapters appropriate for the planned case.

In addition, it is important that the instrumentation is confirmed to be setup and working appropriately before skin incision. The foramen of Monro is not the correct time and place to troubleshoot problems with the monitors, incorrect up-down orientation with the endoscope, and malfunctioning irrigation channels. A systematic checklist approach is the key to avoid these frustrating errors.

Pitfall #2: Inappropriate preoperative planning

Given the keyhole emphasis of MIN, MIN exposures tend to expose less and are thus less flexible than larger exposures. Openings are targeted to the pathology in question and are not robust to large inappropriate deviations from the ideal trajectory. Hence, it is important to spend more time with this approach than one would spend with a larger approach, considering the implications of specific aspects of the intended trajectory. Although some procedures (notably third ventriculostomy) can be performed using stereotyped entry points, most procedures require a thoughtful case-by-case assessment of the individual lesion being treated and its relationship to critical normal structures. Although planning these cases becomes more intuitive with experience, image guidance can be invaluable to those less experienced with MIN. For complicated intraventricular or intracranial lesions, the use of image guidance to plan an idea trajectory and to adhere to this plan is indispensible, and an excellent image registration should be viewed as a critical part of technical success.

Pitfall #3: Getting lost

Second only to beginning the procedure without the appropriate equipment, getting lost is the greatest sin of minimally invasive intraventricular or intracranial surgery, and without conscious efforts to avoid getting lost, it is an easier state to achieve than one would initially think is possible. An inaccurate or inappropriate understanding of the anatomy visualized can provide the unwary surgeon with a false sense of what areas are safe and what areas to avoid, prompting inappropriate actions, with potentially devastating results. A thorough familiarity with the anatomy obtained through dissections and experience obviously lowers the risk of getting lost, especially when combined with image guidance.

There are several common regions encountered during ventriculoscopy that even those familiar with the relevant anatomy can misinterpret, if not aware of these possible mistakes. One well-known error is unknowingly entering the contralateral lateral ventricle, which if not recognized can cause the surgeon to inappropriately enter the wrong foramen of Monro, causing traction and potential injury to both fornices. Another error is mistaking the cerebral aqueduct for the infundibular recess of the third ventricle. Such a misinterpretation can cause the surgeon to perform a third ventriculostomy, just posterior to the mamillary bodies (which is interpreted as being anterior to the mamillary bodies), with devastating injury to the midbrain and/or basilar artery. Hence, it is critical that after gaining ventricular access with the endoscope the surgeon survey the anatomy carefully before making any definitive maneuvers. The choice of correct trajectory, the appropriate confirmation and maintenance of a correct up-down orientation of the endoscope, and the use of image guidance are also important for avoiding these kinds of mistakes. However, the importance of a slow and deliberate assessment of the orientation provided is essential to avoid getting lost.

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